2 Answers
2

Calcium Chloride [dihydrate] (CaCl₂) and chalk (CaCO₃)are two different things.

You should not add salts unless you:

a/ know your water's makeup; you might be able to get most of the relevant details from your municipal water department's yearly report, perhaps even from their website. Otherwise, you can get a test kit, or send a sample to Ward Labs for analysis.

b/ have a target water makeup in mind

Then, you can use a tool (or do the work yourself, I guess; but use a tool) to determine how much of each salt to add to get from where you are to where you want to be. Note that with particularly dark malts, pH adjustment starts to become more of an active requirement, as well.

I recommend against adding salts at this point. At 5 batches in, you probably have other things to focus on to improving your beer (yeast health/pitch rates and fermentation temp control, probably); water adjustment is pretty far down the list.

Hey Jsled - Thank you for the feedback. Pardon the mixup on the wording. I'll have to google around a bit more to find the water report for crystal geyser bottled water. When you mention having a "target" water makeup in mind, how other than "good for porter" could I articulate that makeup?
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Michael MusApr 24 '13 at 19:32

Both dark roasted grains (Chocolate, Carafa, etc) and Calcium Chloride decrease mash pH, so adding both to water which works for Amber Ales sounds like you might need to adjust the water pH up (chalk is one way to do that, but its complicated...)

If you don't want to figure out the water additions now, and you know your "crystal geyser bottled water" makes a good Amber Ale, then I would suggest mashing the dark grains of the Porter separately in some room temp water for a day, and adding that liquid to the boil. You might need to increase the amount of dark grains by 10-15%, but doing it this way ensure that they don't mess with your mash pH.

Hey Graham, Good advice thank you. The bottled water I use has made great amber ale, so good that I consider it my best beer. A fellow brewer recommended that I keep the darker grains aside until after the mash is done, mix them in and then vorlauf, sparge and vorlauf again. Were I not brewing this batch in around 3 hours from now, I'd try your method! Noting it for the next dark brew. LHBS recommended that I add a 1/2 tsp of chalk to each gallon, but I'm going to skip it for now. I'll revisit water conditioning another time.
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Michael MusApr 24 '13 at 21:30

Yeah adding the dark grains right at the end of the mash is pretty much the same as technique I describe, so you should be fine with that. In both cases, the dark stuff won't impact your main mash pH at all. By adding them before the vorlauf, you are dropping your sparge pH by a tiny bit, but that's usually helpful anyway.
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GrahamApr 26 '13 at 13:48